The aim of this study was the establishment of quantification methods for binary mixtures containing a novel polypropylene/polyamide 6-based bicomponent fibre, for which a new generic fibre name has been requested to the European Commission. Application of such methods is requested by EU legislation to enable market surveillance of the compulsorycomposition labelling of textile products. Evaluating the key parameters for quantification, results showed that the b coefficient for the novel fibre (mass loss due to normal pre-treatment) is equal to 0%. In agreement with the members of the European Network of National Experts on Textile Labelling, the value of 1.00% was established as its agreed allowance (moisture regain in standard atmosphere), on the basis of the experimental value of 0.54%. Among the dissolution methods described in Directive 96/73/EC, the new fibre was insoluble in ten, for which the d correction factors (mass loss of the insoluble component) were evaluated. Three of them were additionally validated through an EU collaborative trial according to ISO 5725:1994. The ten established d correction factors were in the range of 1.00–1.01, revealing complete insolubility or up to 1% solubility of the novel fibre in the dissolution reagents. Based on this study, laboratories now have at their disposal methods to quantify the new fibre in binary mixtures with polyester, elastomultiester, polyamide, chlorofibres, certain acrylic and modacrylic fibres, acetate, triacetate, polylactide, certain cellulose fibres and certain protein fibres.

A method for the quantification of a novel polypropylene/polyamide bicomponent fibre in binary mixtures with polyamide was subjected to validation by collaborative trial. Considering the probable acceptance of the novel fibre in Europe, this method would allow market surveillance and antifraud controls needed for consumer protection. The aim of the study was to extend the scope of application of method 11 of Directive 96/73/EC. The method foresaw selective dissolution of the polyamide component using 75% m/m sulfuric acid at room temperature for 1 h. In order to ensure accurate quantification of the blends, two additional rinsings of the residue with the reagent used for the dissolution had to be included in the washing procedure of method 11. Following ISO 5725, a balanced uniform level test was performed, with the participation of seventeen European laboratories, on loop twisted carpet samples of three levels of concentration. The trueness was evaluated considering, as reference, data values obtained from manual separation. The bias varied from 0.06 to 0.49%. Repeatability and reproducibility limits were in the range 0.70–1.04% and 0.97–1.87%, respectively. In agreement with the members of the European Network of National Experts on Textile Labelling, the optimized method was judged fit-for-purpose and the reproducibility limit was established at 2%. Based on this study, the novel fibre can be inserted in the scope of application of method 11 as the insoluble component ( d factor 1.005) and polyamide as the soluble one, provided that modifications are adopted.